Our approach
Side by side

NOW L-Theanine 100 mg vs Yu Sleep

The published reviews of NOW L-Theanine 100 mg and Yu Sleep, lined up: the five scores, what one serving delivers against the studied dose, the real cost per serving and what each label leaves out. Figures as of 22 September 2026.

The short answer

NOW L-Theanine 100 mg scores 6.4/10 against Yu Sleep's 1.8. The widest gap is label transparency: 9 for NOW L-Theanine 100 mg, 1 for Yu Sleep.

These sit in different categories. They are compared because one review names the other as an alternative, so read the dose rows with that in mind.

Pick NOW L-Theanine 100 mg if…

  • you want every amount on the label disclosed
  • tolerability and a well-characterised safety record come first
  • you want a serving that matches the amount used in research

Pick Yu Sleep if…

It does not lead on any criterion we score. Read its review for the case in its favour.

Criterion by criterion

The five criteria every review is scored on, published on the grading page. The overall score is their average.

Evidence for the marketed claim

How strong the research is for what the product is actually sold to do — not for the ingredient in general.

NOW L-Theanine 100 mg5/10Leads
Yu Sleep3/10

Dose against the studied amount

Whether one serving delivers the amount used in the research behind the claim.

NOW L-Theanine 100 mg6/10Leads
Yu Sleep2/10

Label transparency

Whether the Supplement Facts panel is published in readable text and every active amount is disclosed.

NOW L-Theanine 100 mg9/10Leads
Yu Sleep1/10

Value against the generic equivalent

Cost per gram or per dose of the active ingredient, compared with the plainest version of the same thing.

NOW L-Theanine 100 mg6/10Leads
Yu Sleep2/10

Safety and tolerability

Known risks and interactions, how well characterised they are, and whether the label warns about them.

NOW L-Theanine 100 mg6/10Leads
Yu Sleep1/10

Dose against the studied amount

What one labelled serving delivers, placed against the range on each ingredient’s evidence page. Where a label gives no figure, there is nothing to place, and that is the finding.

L-theanineEvidence B

Studied dose: 100–200 mg a dose

  • NOW L-Theanine 100 mg100 mg per capsule (200 mg at the label’s upper dose)In range
  • Yu SleepNot disclosedUndisclosed

GABAEvidence D

Trial range: 100–300 mg a dose

  • NOW L-Theanine 100 mgNot in the formula
  • Yu SleepNot disclosedUndisclosed

Green tea extractEvidence C

No single studied range in label units, so amounts are shown but not placed.

  • NOW L-Theanine 100 mg250 mg per capsule (500 mg at the label’s upper dose)
  • Yu SleepNot in the formula

What it actually costs

Price divided by labelled servings, from a dated listing. A serving is whatever the label calls one, which is why the studied-dose row matters more than the headline figure.

  • NOW L-Theanine 100 mg$0.24 a serving · $21.99 for 90 servings at NOW Foods, checked 22 Sept 2026
  • Yu Sleep$138 for a two-month package, down to $49 a month on the six-month. No per-serving figure: servings not recorded.

Cost to reach a studied dose of L-theanine

  • NOW L-Theanine 100 mg$0.24 · one serving reaches it
  • Yu SleepCannot be worked out: amount or price missing

Label checks

What each label discloses, and what it leaves out. Read from the reviews, not from the marketing.

NOW L-Theanine 100 mg

  • Every active ingredient has a stated amount
  • No third-party certification

Yu Sleep

  • 6 of 7 listed ingredients have no stated amount
  • No third-party certification
  • Scored 1/10 for safety and tolerability

How this comparison is built

  • Scores are the ones already published in each review. Nothing is re-scored for the comparison, and a product leads a criterion only when it outscores the rest.
  • Doses are read from the label rows in each review and placed against the studied range on the matching ingredient page. A figure that is not printed is never estimated.
  • Costs use a dated retailer price divided by labelled servings. Prices in different currencies are never ranked against each other.
  • Only products in the same category, or ones a review names as an alternative, can be compared. Commission never changes what appears here.

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